Fuel cells have been extensively studied for numerous applications, including automotive applications. One of the key components of a fuel cell is the electrocatalyst, the nature of which will impact on both performance and cost of the fuel cell. A typical electrocatalyst is formed from platinum particles on a carbon support. The electrochemical reactions for a fuel cell occur on the surface of the platinum particles, and thus for a given amount of platinum, smaller particles are preferred in order to obtain higher utilization of the platinum as a catalyst. However, there is often an aggregation problem for smaller platinum particles on the carbon support when exposed to fuel cell conditions, the aggregation of the particles requiring additional platinum to ensure a given level of performance. In addition, the tremendous demand for platinum has greatly increased its cost, and thus reducing the amount of platinum used in a fuel cell would greatly aid commercialization of this technology.
In a typical proton exchange membrane (PEM) fuel cell (FC), the PEM is sandwiched between two electrodes, an anode and a cathode. The fuel cell includes a supply of fuel such as hydrogen gas to the anode, where the hydrogen is converted to hydrogen ions (protons) and electrons. Oxygen is supplied to the cathode, where the oxygen, hydrogen ions conducted through the PEM, and electrons conducted through an external circuit combine to form water. Electrocatalysts are used to facilitate these electrode reactions. For better fuel cell performance, the catalytically active material (platinum) should be in contact with an electron-conducting material such as carbon black that conducts the electrons, and a proton conductor (the PEM) that conducts the protons. However, in a conventional PEM fuel cell, if platinum is located in pores of the carbon black, contact with the PEM may be lost, reducing effectiveness.